There is renewed interest in private networks because of the evolving offer in terms of telecommunications services, because of voice/data/picture convergence, and because of the penetration of computers into the home. A private network generally includes a gateway that interfaces the private network with an access network that is external to the private network and that is managed by a telecommunications operator. The gateway generally also has the functions of organizing exchanges between the private network equipments and of isolating local traffic from external traffic.
At present there are several solutions for implementing private networks. Non-cable solutions use radio or free space optical techniques. However, radio solutions lack confidentiality, which compromises the security of the data. They are also vulnerable because they are readily affected by interference caused by environmental conditions and furthermore offer a limited bit rate. Solutions based on unguided infrared optics also have their limitations. In fact, their bit rate is limited if the sender and the receiver are not in direct line of sight of each other. To obtain a higher bit rate, it is necessary for the sender and the receiver to be in line of sight of each other, which represents a severe constraint for the user.
Other solutions, using cables, rely on a cabling architecture. Numerous media exist for providing such cabling, essentially copper in the form of twisted pairs, coaxial cables, or power cables, and monomode or multimode silica, polymer, or other material optical fibers.
Different standards have appeared for using these media, promoted by telecommunications, computers, and electronics, audio, and video interests. The standards that have been developed are protocols such as ATM (Asynchronous Transfer Mode), IP (Internet Protocol), Ethernet, etc., which are independent of the physical medium and define particular specifications for the format of the data according to the medium used.
Cable solutions using copper cables in the form of twisted pairs, promoted by telecommunications interests, make it possible to use the access network and to extend it to the home. In this case, the data is conveyed in a standard telecommunications format, such as the IP or ATM format. However, these solutions continue to suffer from limitations because they cannot convey signals necessitating high bandwidth. For example, twisted pair cables cannot carry UHF signals from a UHF television antenna. These solutions therefore do not make it possible to integrate new developments.
Where coaxial cables are concerned, experience shows that, in the residential context, existing networks are linked solely to the distribution of UHF television signals. These networks are often of mediocre quality and the cabling topology does not correspond to that of a private network. Complete recabling is therefore necessary in practice, yielding a solution of too limited performance to face up to new developments.
With the recent expansion of the HomePlug Powerline Alliance AV standard, it is now possible to produce a residential network via the electrical mains wiring. The benefit of this technique is that it is not necessary to install any additional cables, and it should be possible to transmit useful bit rates of around 100 mega bits per second (Mbps) for real bit rates of 200 Mbps, although current solutions offer a bit rate of the order of only a few Mbps. The technique uses dedicated modems to convey the high bit rate signals over the electrical mains wiring. This technology is very attractive, but the bit rate is still limited and all the data must be formatted in the same manner, and so combining heterogeneous services cannot be seriously envisaged. In the context of increasing the bit rate of residential networks, this technology is therefore equally inadequate to meet the constraints of the residential core network.
Finally, another, more promising solution using optical fiber cables has been envisaged. Given the service life that indoor cables must offer and the uncertainty as to the bandwidth requirements during the service life of the network, optical fiber cables constitute the most open-ended solution. One such solution uses an architecture based on the architectures of PON (passive optical network) type access networks. This solution is shown in the diagram of FIG. 1. This kind of architecture includes a gateway GTW connected by optical fiber cables C1-C4 and via a 1 to N optical coupler 100 to a plurality of equipments, for example a personal computer 10, a television decoder and receiver 20, a printer 30, etc. In this case, the gateway is situated at the head end of the network and it is the gateway that manages the traffic, since all of the data exchanged passes in transit through it. That traffic may go from an operator's access network to a terminal in the private environment or vice-versa. Thus the computer 10 may communicate with the printer 30 or the external network via the optical coupler 100 and the gateway GTW.
This solution still has its limitations, however. In fact, it does not enable two remote equipments to dialogue directly without passing through the gateway, which has to manage everything necessary for establishing communication between the two equipments. The fact that all the traffic, even local traffic between two private equipments, must pass in transit through the gateway again requires the corresponding signals to be transposed to a precise format, comprehensible to the gateway. Consequently, this solution is limited in terms of the domestic services it is able to deliver. For example, it cannot relay signals from a UHF television antenna or relay signals from an audio source to remote sound reproduction devices in another room. With this type of architecture, the domestic services provided are therefore very limited and users will not be able to access all the services that they require.
Consequently, regardless of the medium adopted, all current solutions impose constraints on the format of the information transported. Private networks implemented until now make all services offered by the external access network that the user wishes to transport compatible with the gateways, i.e. convey data in the same single format.